1) Field of the Invention
This invention relates to a production process of chlorine, in which a fluidized bed reactor is used. More specifically, this invention is concerned with a process for producing chlorine by oxidizing hydrogen chloride gas with an oxygen-bearing gas in a fluidized bed reactor equipped with perforated plates.
2) Description of the Related Art
The oxidative reaction of hydrogen chloride for the production of chlorine has been known as the Deacon process for many years. Numerous catalysts have heretofore been proposed for this reaction (G.B. Patent Nos. 584,790, 676,667 and 846,832).
A variety of processes have also been proposed for the preparation of a catalyst which is composed of a chromium oxide as a principal component and is useful in a production process of chlorine by oxidation of hydrogen chloride (Japanese Patent Application Laid-Open Nos. 136902/1986, 275104/1986 and 113701/1987; Japanese Patent Application Nos. 112592/1986 and 148055/1986).
In addition, a process has also been proposed for the production of chlorine by oxidation of hydrogen chloride in the presence of such a catalyst in a fluidized reactor (Japanese Patent Application No. 157812/1987).
A fluidized bed reactor generally has a gas diffuser plate in a bottom part thereof, and a catalyst is placed above the gas diffuser plate. A feed gas mixture is charged upward through the gas diffuser plate, so that the feed gas mixture is brought into contact with the catalyst to induce a chemical reaction.
Because of the structure mentioned above, the catalyst layer takes the form of a fluidized layer and the feed gas mixture is brought as bubbles into contact with the catalyst to undergo the reaction. However, the bubbles join together into greater bubbles as they ascend through the fluidized layer. As a result, the efficiency of contact is lowered in an upper part of the catalyst layer. So long as the catalyst has extremely high activity, the reaction can ordinarily be brought to completion by simply mixing the feed gas mixture with the catalyst and the efficiency of contact between the feed gas mixture and the catalyst would not affect the yield of the reaction.
A reduced efficiency of contact will however lead to a lowered yield where the reaction velocity is slow.
When producing chlorine by oxidation of hydrogen chloride in the presence of a catalyst as described above, the catalyst has high activity but its bulk density is relatively high. The catalyst therefore tends to promote the joining of bubbles into greater bubbles. This joining of bubbles inevitably results in a lowered efficiency of contact between the catalyst and the feed gas mixture. As a result, the conversion of hydrogen chloride into chlorine is lowered. The efficiency of facilities is reduced corresponding, leading to a substantial loss in economy.